Decisive Battles of the American Civil War, Vol. 1 lets you take the place of commanding generals in six battles of the American Civil War: first Bull Run, Shiloh, second Bull Run, Antietam, Fredericksburg, and Chancellorsville. In that role, players not only issue orders but take actions such as sleeping and determining their level of personal participation in the battle. Players also experience the inverse relationship of responsibility to control. Orders can only be issued to brigades near the mobile command center, and objectives set only at the division level, with some variation per historic orders of battle. Subordinates, who are rated by leadership and experience, will then adapt these orders to their view of the battle, to the point of taking actions quite different from their orders. Once they're out of communications range, players can only hope for sound judgement or miraculous foresight.
The result is a fast-paced simulation (one hour per turn) of important moments in Civil War history. In some battles, the player has just one or two opportunities to issue orders to a significant portion of the army. At a distance, the enemy is invisible, and intelligence on enemy units prior to engagement is limited to formations. Upon engagement, casualty counts and morale are the player's main focus. Players may override subordinate orders to pull nearby brigades into reserve, although one turn's hesitation can demonstrate how quickly a cohesive resource of men and artillery can become useless on the battlefield.
Two-thirds of the play screen are devoted to a scrollable map, supplemented by a printed map sheet showing all of the battlefields. The other third of the screen gives terrain and unit descriptions, battle reports, and terse command menus. Victory is determined by a tally of casualties and controlled objectives. Difficulty can be varied in a number of ways, most notably by toggling full communication and invisible movement. Two players may face-off in hot-seat mode, or a single player may face the computer or just observe the computer controlling both sides. The game manual describes in detail how combat effectiveness and other key calculations are made. Two design utilities allow what-if modifications of the included scenarios as well as creation of entirely new ones on custom maps and terrain.